Methods are known in the art for glass manufacturing wherein glass-forming batch ingredients are compacted into agglomerates and then are dried and heated in a chamber by a direct contact with flue gases from a glass melting furnace so as to produce free-flowing agglomerates which are then conveyed and discharged to the glass melting furnace.
Methods are also known in the art for preheating glass batch which include the steps of feeding cold particulate glass batch raw materials into one end of a rotating heat-transfer drum and feeding hot media of larger particle size than the batch particles into the other end of the heat transfer drum. The glass batch moves in direct and immediate physical contact with the heated media, with the batch flowing from the cold end to the hot end of the drum and the media flowing from the hot end to the cold end of the drum. The heat transfer media is made of a durable material such as ceramic material, steel, stainless steel, aluminum or gravel.
Phenolic resinous condensation products, and more specifically, phenol-formaldehyde resins, processes for their production and equipment for manufacture thereof are well known. Commercially, two main types of reactions involving different ratios of phenol to formaldehyde with acid and alkaline catalysts, respectively, are employed to produce commercially important curable phenol-formaldehyde resins. Through use of various reactants, catalysts, and proportions of each, and control of reaction conditions and the like, curable resins of different properties and types are obtained. In the presence of basic catalysts, such as sodium hydroxide, calcium hydroxide, tertiary amines, ammonia and the like, and more than one mole of formaldehyde per mole of phenol, phenol and formaldehyde condense to form a phenolic resole or an A-stage resin which is fusible and soluble in alkalis. Such resoles, upon further advancement of the reaction, proceed to a B-stage, where they are called resitols. Upon still further advancement of the reaction, they proceed to resites or C-stage resins, which are relatively insoluble and infusible products.
The binder composition can be embodied in the usual manner for the fabrication of structural tile, bonded insulation or pipe wrap, as by flooding a collected mat of glass fibers and draining off the excess or by applying the binder composition onto the glass fibers during mat formation. For cure, the mass is heated to a temperature in excess of 350.degree. F., and preferably within the range of 500.degree.-650.degree. F. for a time sufficient to advance the components. The time and temperature will depend in part on the amount of binder in the final structure and the thickness and density of the structure that is formed. For a structure having a thickness ranging from 1/2 to 1 inch, a time ranging from 1-5 minutes will be sufficient at a temperature within the range of 500.degree.-600.degree. F.
The means by which the glass fibers are formed for use in the described system may vary widely. Use can be made of discontinuous or staple glass fibers such as are formed by the rapid attenuation of multiple streams of molten glass by high pressure streams of air or steam directed angularly downwardly onto the streams of molten glass flowing therebetween. Instead, use can be made of continuous or textile fibers such as are formed by the rapid attenuation of molten streams of glass. The continuous glass fibers may be employed in the form of mats fabricated thereof as by swirling the endless filaments or strands of continuous fibers, or they may be chopped or cut to shorter lengths for mat or batt formation.